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Title:Assessment of thermal mass property for energy efficiency and thermal comfort in concrete office buildings
Author(s):Ghoreishi, Amirhossein
Director of Research:Ali, Mir
Doctoral Committee Chair(s):Ali, Mir
Doctoral Committee Member(s):Strand, Rick; Murray, Scott; Armstrong, Paul; El-Gohary, Nora
Department / Program:Architecture
Degree Granting Institution:University of Illinois at Urbana-Champaign
heating and cooling energies
thermal comfort
energy efficiency
concrete thermal mass
Abstract:The increasing use of concrete as a material propelled by the recent advancements in concrete technology is facing the prospect of its massive growth in the building sector worldwide. In addition to its positive structural characteristics, concrete has an inherent thermal mass feature that is known to save heating and cooling energies. However, such benefits need to be quantified so these benefits can be augmented and exploited. Concrete is also known to provide thermal comfort in a building, a prospect that can be related to its thermal mass property. While some studies have separately explored the effect of thermal mass’s thickness or surface area on building energy and thermal performance in a limited way, only a few have focused on both factors in the same study in detail and for that matter their combined effects, and even fewer have taken into account the distribution of thermal mass in a building. With an integrated approach, this present research has aimed for addressing all three variables: the thickness and distribution of concrete thermal mass in the building envelope; the distribution of thermal mass in a building’s configuration; and their effectiveness in reducing building energy consumption in office buildings and in improving its thermal comfort. The research methodology mainly focused on the quantitative methods with the use of building energy simulation tools including eQUEST, Design Builder, Energy Plus, and Atherna Impact programs. The Department of Energy (DOE) benchmark office building was considered as reference building model and the architectural design variables, including wall thicknesses and exterior thermal amass area, were selected to represent primary thermal mass. The slab thickness and interior wall layouts were selected to represent the secondary thermal mass. The eight climatic conditions of 1A (very hot and humid); 2B (hot and dry); 3C (warm and marine); 4B (mixed-dry); 5A (cool and humid); 6A (cool and marine); 7 (cold and dry); and 8 (very cold) will be assumed as representatives of all 16 U.S. climate zones. Lastly, life cycle assessment (LCA) and life cycle cost (LCC) analyses were conducted for a selected number of case models. This study has indicated that the primary thermal mass elements such as wall thickness and thermal mass area have more effects on building energy and thermal comfort performance compared to secondary thermal mass elements such as slab thickness and interior walls. Therefore, the main thermal mass-related design emphasis needs to be on its implementation in the building envelope. Energy efficiency and thermal comfort are generally conflicting criteria in building design in that the more the energy is saved, the less is the thermal comfort. Therefore, a design challenge is to determine the optimal combination of energy saving and thermal comfort. In terms of the optimization of energy usage and thermal comfort, this research shows that better energy performing thermal mass scenarios also have better thermal comfort performance. The utilization of thermal insulation along with a primary thermal mass, i.e., wall thickness, can also enhance the energy saving effects of thermal mass. In terms of LCA, an increase in wall thickness, for example, has relatively improved the environmental impacts of the building and has helped reduce the cost of building operation in its life cycle. For future research, the effects of design form and building height on the effectiveness of thermal mass in improving building energy and thermal comfort performance can be studied. Furthermore, different types of perimeter wall assemblies and glazing, especially with low-e coating can be combined with thermal mass to study the benefit from other energy saving recommendations in conjunction with thermal mass. In terms LCC, for instance, besides the cost of concrete materials, assembly, maintenance and demolition costs associated with concrete should be determined to assess the actual benefits of thermal mass in comparison with its additional costs.
Issue Date:2015-04-21
Rights Information:Copyright 2015 Amirhossein Ghoreishi
Date Available in IDEALS:2015-07-22
Date Deposited:May 2015

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